If your window is hard to open or close it could be that the frame is expanding or shrinking due to the weather. Heat will make wooden frames expand, making is harder to get them open in the summer. While the cold usually make them shrink, if they are porous and have soaked up any moisture, and that freezes, the ice can also make the wood expand and the window stick.
To fix this, you can use brute force, wait until the temperature changes, or use use the thin blade of a putty knife and jimmy the window open. Be very careful not to damage the frame, though!
You need to be very wary of leaks around a window and where they are coming from. If it is the window itself, then plug them if possible or replace them if you have to. Be careful that the leak isn't coming from the areas, though. Check that the signs that you can see are not from rising damp or a crack in the water sealant on the outside of the wall.
Moldy windows are unsightly and unhygienic. They can cause health issues, especially breathing problems. Mould occurs around window frames and sills mostly due to condensation. This is when moisture in the air is turned back into liquid when it hits the glass of your window. You can prevent this by making sure your home is aired out. Open the windows or use a dehumidifier. Make sure that you always put the extractor on after a bath or a shower to get rid of any excess moisture in the air.
Drafty windows are not a good idea. Not only is it unpleasant to live in a drafty home, but they are also costing you money too. If you have a draft, then air can get in, that means the hot air that you are paying for can also get out. Drafty windows are not energy efficient because it takes more energy to get the room to the same temperature as the heat is escaping. If possible block small drafts with caulking. If there are bigs gaps, it means the window no longer fits properly, and it's time to invest in some quality double glazing.
You are always cleaning them
Cleaning the windows is a big chore, so reducing the amount that we have to do this, is a good thing. But how can you clean your wonders less without getting stuck in a dark and dingey room?
The secret is to minimise the amount of dirt that they come into contact with. Of course, you can stand outside your home with a leaf blower distracting any stray speck of dust away from your precious windows. But people may think you have lost it, and you'll never get anything done.
Instead keep to these easy rules. Don't burn candles or your BBQ near to your windows as the door will stick to them. Also, make sure that if you are using the oven in the kitchen that you have the extractor on. It's so easy for grease to stick to your windows which will in turn act like a magnet for any other dirt or dust in the house!